Intrinsic properties and strengthening mechanism of monocrystalline Ni-containing ternary concentrated solid solutions

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 695; no. C; pp. 74 - 79
• Main Authors: Jin, K., Gao, Y.F., Bei, H.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 17.05.2017; Elsevier BV; Elsevier
• Subjects: Alloy systems; Alloying elements; Alloys; Anisotropy; Binary alloys; Binary systems; Bulk modulus; Elastic anisotropy; Elastic constants; Elastic properties; Hardness; High entropy alloys; Intermetallic compounds; Iron compounds; MATERIALS SCIENCE; Mechanical properties; Medium/high entropy alloys; Modulus of elasticity; Nanoindentation; Nickel compounds; Physical properties; Shear modulus; Single crystals; Solid solution alloys; Solid solution strengthening; Solid solutions; Solution strengthening; Specific heat; Strain hardening; Ternary systems; Ultrasonic testing; Solid solution alloys; Elastic constants; Solid solution strengthening; Medium/high entropy alloys; Nanoindentation
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2017.04.003

Ternary single-phase concentrated solid solution alloys (SP-CSAs), so-called "medium entropy alloys", not only possess notable mechanical and physical properties but also form a model system linking the relatively simple binary alloys to the complex high entropy alloys. The knowledge of their intrinsic properties is vital to understand the material behavior and to prompt future applications. To this end, three model alloys NiCoFe, NiCoCr, and NiFe-20Cr have been selected and grown as single crystals. Their elastic constants have been measured using an ultrasonic method, and several key materials properties, such as shear modulus, bulk modulus, elastic anisotropy, and Debye temperatures have been derived. Furthermore, nanoindentation tests have been performed on these three alloys together with Ni, NiCo and NiFe on their (100) surface, to investigate the strengthening mechanisms. NiCoCr has the highest hardness, NiFe, NiCoFe and NiFe-20Cr share a similar hardness that is apparently lower than NiCoCr; NiCo has the lowest hardness in the alloys, which is similar to elemental Ni. The Labusch-type solid solution model has been applied to interpret the nanoindentation data, with two approaches used to calculate the lattice mismatch. By adopting an interatomic spacing matrix method, the Labusch model can reasonably predict the hardening effects for the whole set of materials.